Watercraft are currently retrieved from a body of seawater onto a retrieval ship, involving use of a ramp projected from the stern of the ship onto which the watercraft is landed. Such ramp landing of watercraft often effects impact damage thereof because of hydrodynamic turbulence and ship motion, imposing displacement of the watercraft on the ramp. It is therefore an important object of the present invention to avoid the foregoing watercraft damage imposing problems during retrieval of watercraft onto ships.